-LRB- CNN -RRB- -- The Syrian government is freeing some activists while arresting hundreds of others in its back-and-forth bid to placate protesters and crush dissent , a human rights lawyer said .

Attorney Razan Zaytouni sent CNN a list Sunday naming more than 500 people she said have been arrested since the start of the unrest a couple of weeks ago . Roughly half of those people have since been released , the list shows .

CNN could not independently confirm details of the report . Last week the Syrian Arab News Agency said that a wave of arrests came as government security forces were searching for members of an `` armed group '' that killed `` a number of citizen and security forces . ''

SANA reported that an unidentified official said snipers from the group fired at citizens and security forces from rooftops . This is disputed by activists and eyewitnesses who told CNN that government snipers fired shots at unarmed protesters and government forces beat demonstrators .

Protesters in Syria are upset at what they see as the nation 's heavy-handed rule . Opponents of the government allege massive human rights abuses and are calling for political and economic reform . They also want the release of all political prisoners and an end to emergency law .

The emergency law allows the government to make preventive arrests and override constitutional and penal code statutes . In effect since 1963 , it also bars detainees who have not been charged from filing court complaints and from having a lawyer present during interrogations .

Zaytouni said she is part of a group of lawyers that has volunteered to help defend political prisoners .

`` But our role is superficial . There is no judicial system in Syria and the security apparatus arrests people and send them to courts directly , '' she said .

Amnesty International estimated late last month that at least 93 people were believed to have been arrested by Syrian security forces between March 8 and March 23 and held in unknown locations .

The real number arrests is likely to be `` considerably higher , '' the rights group said , adding that the detained include students , intellectuals , journalists and activists .

Zaytouni spoke the same day the family of an imprisoned activist said he was freed .

Mohammad al-Abdallah told CNN his brother was released Sunday after more than five years in prison . Omar al-Abdallah , 26 , was accused of `` taking actions and making threat -LRB- ening -RRB- statements against the state in Syria , '' his brother said .

Their father remains a political prisoner , he added .

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A rights lawyer says more than 500 people have been arrested in the recent crackdown

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Roughly half of those people have since been released , she says

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Omar al-Abdallah is freed after 5 years in prison , his brother says

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Protesters in Syria are calling for the release of all political prisoners